1. Technical Field
The presently disclosed subject matter relates to a semiconductor light emitting device, and in particular, to a semiconductor light emitting device having a plurality of semiconductor light emitting elements and a wavelength conversion layer including a wavelength conversion material, such as a phosphor.
2. Description of the Related Art
Recent semiconductor light emitting elements that include light emitting diodes have been improving in terms of high power and high brightness characteristics. In connection with this improvement, such semiconductor light emitting elements have recently been applied to new fields of illumination devices, including general lighting, street lighting, headlamps, and the like. In recent years, illumination devices have included a plurality of types of semiconductor light emitting elements that each have different emission wavelengths such that driving conditions can be adjusted for, and respective semiconductor light emitting elements can be controlled in order to vary the color temperature as a whole.
As an example of the structure of such an illumination device that is capable of varying color temperature, an illumination device is proposed in Japanese Patent Application Laid-Open No. 2007-059260. In this publication, the illumination device includes a daylight semiconductor light emitting element, an incandescent color semiconductor light emitting element, and a green color semiconductor light emitting element. The illumination device can emit light with color temperatures ranging from daylight color to incandescent lamp color (on the blackbody radiation trajectory) with the help of the green color semiconductor light emitting element. In another configuration, an incandescent color semiconductor light emitting element and a blue semiconductor light emitting element are used in combination to emit light with color temperatures ranging from daylight color to incandescent lamp color and can be linearly changed.